No abstract

1 Intravenous loading with 500 ml of 2.7% saline increased the clearance of PAH and inulin and urine sodium excretion in 14 healthy subjects. 2 Intravenous propranolol (0.075 and 0.15 mg/kg) did not alter PAH or inulin clearance at rest but abolished the increase expected during saline infusion. There was no consistent effect on urinary sodium excretion. 3 Intravenous nadolol (0.05 and 0.75 mg/kg) reduced resting PAH and inulin clearances by up to 25%. Both clearances fell significantly during saline infusion but natriuresis was not significantly reduced in spite of the changes in renal function. 4 There was no evidence from these studies in normal volunteers that nadolol confers any advantages over propranolol in its effects on renal function.

Membrane leaves the rhabdom of Limulusphotoreceptors either by transient shedding at dawn or throughout the day by light-driven shedding. We examined whether the light trigger for transient shedding and the light drive for light-driven shedding are localized properties of the illuminated photoreceptors or whether they are an array property of the retina. Four experiments were conducted during which the lateral eye was exposed to one of a variety of different illumination patterns for a day, fixed, dissected and cut into serial frozen sections. Immunocytochemistry with different antibodies to Limulus opsin and arrestin revealed the results of the two processes in a distinguishable way. Eyes stimulated with whole-eye illumination had both types of shedding or just light-driven shedding when transient shedding was blocked by cutting the optic nerve. Eyes exposed to whole-eye darkness had neither type of shedding. However, when only half of an eye was exposed to light, the dark half had the same kinds of shedding as the lighted half. We conclude that the signals to trigger or drive shedding must be communicated laterally from illuminated ommatidia to unilluminated ommatidia. Rhabdom shedding is an array property.